Research On BTC's Chase Decoding Algorithm

The thesis presents a modified algorithm focusing on decoding of block turbo codes (BTC). The suggested algorithm can shorten the time-delay and reduce the complexity in BTC decoding. Based on the iterative Chase decoding algorithm that is a fundamental decoding method employed in the thesis, an improved decoding scheme, called adaptive-threshold Chase (ATC) algorithm, is proposed. The new approach can reduce the decoding complexity of the iterative Chase algorithm. The idea is based on excluding some of the least reliable bits from those being processed according to a certain reliability threshold. The threshold function was partially explained from the point of view of mathematics.Simulation results have showed that the proposed algorithm is less complicated and faster to be executed. Compared with iterative Chase algorithm, the proposed adaptive-threshold Chase algorithm can achieve significant performance.Using programmable module design with C++, simulations of the decoding algorithms are implemented. The simulation results are achieved for a communications system with binary phase shift keying (BPSK) on an additive white Gaussian noise (AWGN) channel. For modified algorithm, the performance has been compared. Finally, concluding remarks are given.